<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>1_引出生命周期</title>
    </head>
    <body>
        <!-- 准备好一个“容器” -->
        <div id="test"></div>

        <!-- 引入react核心库 -->
        <script type="text/javascript" src="../js/react.development.js"></script>
        <!-- 引入react-dom，用于支持react操作DOM -->
        <script type="text/javascript" src="../js/react-dom.development.js"></script>
        <!-- 引入babel，用于将jsx转为js -->
        <script type="text/javascript" src="../js/babel.min.js"></script>


        <script type="text/babel">
            //创建组件
            //生命周期回调函数 <=> 生命周期钩子函数 <=> 生命周期函数 <=> 生命周期钩子
            class Life extends React.Component {

                state = {opacity: 1}

                death = () => {
                    //卸载组件
                    ReactDOM.unmountComponentAtNode(document.getElementById('test'))
                }

                //组件挂完毕
                componentDidMount() {
                    console.log('componentDidMount');
                    this.timer = setInterval(() => {
                        //获取原状态
                        let {opacity} = this.state
                        //减小0.1
                        opacity -= 0.1
                        if (opacity <= 0) opacity = 1
                        //设置新的透明度
                        this.setState({opacity})
                    }, 200);
                }

                //组件将要卸载
                componentWillUnmount() {
                    //清除定时器
                    clearInterval(this.timer)
                }

                //初始化渲染、状态更新之后
                render() {
                    console.log('render');
                    return (
                        <div>
                            <h2 style={{opacity: this.state.opacity}}>React学不会怎么办？</h2>
                            <button onClick={this.death}>不活了</button>
                        </div>
                    )
                }
            }

            //渲染组件
            ReactDOM.render(<Life/>, document.getElementById('test'))
        </script>
    </body>
</html>